Migrions Identified as Hybrid Structures Accelerating Viral Spread

Scientists have identified a new type of virus–cellular structure hybrid, called Migrions, which form when vesicular stomatitis virus (VSV) components are packaged into migrasomes during cell migration. This discovery was made by teams at Peking University Health Science Center and Harbin Veterinary Research Institute and published in Science Bulletin.

Migrions are large, virus-like entities that contain VSV nucleic acids inside and display the VSV-G protein on their surface. These structures are distinct from standard VSV particles that exist freely in the extracellular space.

Unlike conventional viral transmission methods, Migrions can deliver several viral genome copies to a new cell at once, which accelerates the replication process in recipient cells. In addition, Migrions have the capacity to co-transmit different viruses simultaneously, a feature not observed with other extracellular vesicle-based viral spread mechanisms.

Entry of Migrions into recipient cells occurs through endocytosis and does not require specific cell surface receptors. Once inside, acidic conditions activate the VSV-G protein, allowing the Migrion to fuse with endosomes and release its viral contents.

What the numbers show

• Findings published in Science Bulletin in 2025
• Research involved scientists from two Chinese institutes
• Migrion-mediated infection in mouse models led to higher rates of severe disease and death compared to free virus infection

In experimental studies using mouse models, infection mediated by Migrions resulted in more severe outcomes, including lung and brain infections, encephalitis, and frequent mortality. These effects were more pronounced than those observed with infection by free-floating virus particles.

Migrasomes, the cellular structures involved in forming Migrions, are extracellular vesicles produced during cell migration. They were previously recognized for their role in transferring cellular materials such as mRNA and proteins between cells.

Prior research has shown that migrasomes can participate in the spread of other viruses, including poxviruses like vaccinia virus and herpes simplex virus type 2, by releasing vesicles that contain viral particles capable of infecting additional cells.

The identification of Migrions introduces a new model for viral dissemination, as it directly links viral transmission to the process of cell migration. This hybrid structure challenges earlier understandings of how viruses can spread between cells.

* This article is based on publicly available information at the time of writing.